There are ground scent and air scent dogs. Not necessarily breed specific, but some breeds will do better at one that the other. We raise beagles for rabbit hunting. They are primarily ground scent, bloodhounds are the same. But breeds like pointers and coon hounds are primarily air scent. You can generally tell by how they track a trail what type they are using (head up=air scent, head down=ground scent) although some will probably use a combination of both. Also dogs can be trained to find all sorts of scents, so some may be trained to find living people, other cadavers, some explosive, some technology (like cell phones), others fruit, or drugs.
